Pitch and rake gauge for a propeller

ABSTRACT

An apparatus and method involves the use of a gauge to measure the pitch and rake of a blade on a propeller. The gauge has a rotational sensor that determines relative rotation of a measurer. The measurer includes a pitch sensor and a rake sensor. The rotational sensor communicates with a display, which provides an output representative of pitch or rake of the blade based on signals received from the rotational sensor.

RELATED APPLICATION

[0001] The present application claims the benefit of United StatesProvisional Patent Application Serial No. 60/264,103, filed Jan. 25,2001, the complete disclosure of which is hereby expressly incorporatedby reference.

BACKGROUND

[0002] The present invention relates to propellers, and particularly toa device for measuring the pitch and rake of a propeller. Moreparticularly, the present invention relates to a pitch and rake gaugecapable of pivotable movement about an axis, the pivotable movementbeing measured with digital accuracy.

[0003] In the disciplines of manufacturing and repairing propellers usedin boats, planes, and the like, it is desirable to determine with somedegree of accuracy the pitch and rake at numerous points on thepropeller blades. As used herein, “pitch” relates to the theoreticaldistance a propeller would advance longitudinally (due to the slope ofthe blade) in one revolution of the propeller. “Rake,” as used herein,relates to the inclination of the blade surface from the perpendicular.

SUMMARY

[0004] According to the disclosure, a pitch and rake gauge measures thepitch and rake of a blade on a propeller. The gauge comprises apropeller mount configured to support a propeller thereon. A measurer iscoupled to the propeller mount and adapted to engage the blade in astationary position. A rotational sensor gauges rotational movement ofthe measurer and provides signals representative of the gaugedrotational movement. A display receives the signals and provides anoutput based on the signals.

[0005] In the disclosed embodiment, the rotational sensor is coupled tothe propeller mount and is adapted to move between a pitch-sensing modeand a rake-sensing mode. The rotational sensor is illustratively anoptical encoder. The rake sensor includes a straight-edge configured toextend along a radial line relative to the blade of the propeller. Thepitch sensor includes two feet in spaced-apart relation, the two feetbeing configured to contact the propeller blade at two pointssubstantially equally distant from the axis of the propeller.

[0006] The gauge illustratively includes an arm extending radiallyoutwardly from the propeller mount, and a support member attached to thearm. The pitch and rake sensors are rotatably mounted upon the supportmember.

[0007] The disclosure also contemplates a method of measuring acharacteristic of a blade on a propeller having an axis. The methodincludes the steps of positioning the propeller on a propeller mount,connecting a measurer to the propeller mount, assigning a neutralposition for the measurer from which rotational measurements will bebased, and moving the measurer into contact with a selected position onthe propeller blade while rotating the measurer as necessary. Therotation of the measurer relative to the neutral position is thendetermined, and an electronic indication of the rotation of the measurerrelative to the neutral position is provided.

[0008] According to the disclosure, the neutral position-assigning stepincludes zeroing the measurer by placing it in contact with acalibrating platen. A pivot member carries the rake sensor and the pitchsensor, the pivot member presenting one of either the rake sensor andpitch sensor to the propeller blade in order to determine either therake or the pitch of the blade.

[0009] Additional features of the invention will become apparent tothose skilled in the art upon consideration of the following detaileddescription of preferred embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The detailed description particularly refers to the accompanyingfigures in which:

[0011]FIG. 1 is a front diagrammatic view of a pitch and rake gauge fora propeller, showing the propeller positioned on a propeller mount and aradial position arm coupled with the propeller mount and suspended abovethe propeller, the radial position arm supporting a support member witha pitch sensor, a rake sensor, and a rotational sensor in communicationwith the pitch sensor and the rake sensor, the radial position arm andsupport member cooperating to position the pitch sensor, the rakesensor, and the rotational sensor above a calibrating platen prior tomeasurement of the pitch or rake of the propeller;

[0012]FIG. 2 is a side diagrammatic view of the gauge of FIG. 1 showingthe pitch sensor coupled to the rotational sensor and pivoted forcontact with a face of a propeller blade, the rotational sensorresponding to pivoting of the pitch sensor by the transmission ofsignals to the output device of FIG. 1;

[0013]FIG. 3 is a diagrammatic view of the gauge similar to that of FIG.2, showing instead the rake sensor viewed from the front and positionedto contact the face of the propeller blade, the rotational sensorresponding to relative pivoting of the rake sensor with signals to theoutput device of FIG. 1;

[0014]FIG. 4 is a top diagrammatic view of the gauge of FIG. 1, showingthe rake sensor rotated to the uppermost (visible from the top) positionsuch that the pitch sensor is positioned (not visible) below the rakesensor and ready to measure the pitch of the propeller blade (shown inphantom);

[0015]FIG. 5 is a side diagrammatic view of the gauge of FIG. 4 takenalong the lines 5-5, showing the rake sensor in its uppermost unusedposition, the pitch sensor in the lowered position and ready for zeroingon the calibrating platen and the eventual measuring of the pitch of thepropeller blade (shown in phantom);

[0016]FIG. 6 is a side diagrammatic view of the gauge similar to that ofFIG. 5, showing the pitch sensor being zeroed while contacting thecalibrating platen;

[0017]FIG. 7 is another side diagrammatic view of the gauge similar tothat of FIG. 6, showing the pitch sensor in a rotated position as it isplaced in contact with the propeller blade (shown in phantom), whereinthe rotational sensor senses the rotation of the pitch sensor relativeto the zeroed position of FIG. 6 and transmits signals representative ofthe rotation to the output device;

[0018]FIG. 8 is a top diagrammatic view of the gauge similar to that ofFIG. 4, showing the pitch sensor after it has been rotated about an axisparallel to the propeller mount axis and after the pitch sensor and rakesensor have been further rotated about an axis passing through therotational sensor such that the pitch sensor is in its uppermost(visible from the top) unused position and the rake sensor (not visible)is ready to measure the rake of the propeller blade below (shown inphantom);

[0019]FIG. 9 is front diagrammatic view of the gauge shown in FIG. 8,illustrating the rake gauge in the lowered position and ready forzeroing on the calibrating platen for eventual measurement of the rakeof the propeller blade (shown in phantom);

[0020]FIG. 10 is a front diagrammatic view similar to that shown in FIG.9, illustrating the rake sensor being zeroed while it is in contact withthe calibrating platen;

[0021]FIG. 11 is a front diagrammatic view similar to that shown in FIG.10, illustrating the rake sensor in a rotated position as it is placedin contact with the propeller blade (shown in phantom), wherein therotational sensor senses the rotation of the rake sensor relative to thezeroed position of FIG. 10 and transmits signals representative of therotation to the output device;

[0022]FIG. 12 is a top view of a propeller showing radially distancedcircumferential lines representative of the lines on which pitch couldbe measured, and showing a radially extending line representative of aline on which rake could be measured;

[0023]FIG. 13 is a side view of the propeller of FIG. 12, showing theradially distanced lines for measuring pitch and the radially extendingline on which rake could be measured;

[0024]FIG. 14 is a perspective view of one embodiment of the gauge,showing the rake sensor supported above the propeller blade, and showingthe pitch sensor in the unused position, rotated away from the propellerblade, both the rake sensor and the pitch sensor capable of beingrotated about an axis through the support member, the axis beingcommunicatively coupled to the rotational sensor, which is specificallyan optical encoder;

[0025]FIG. 15 is a perspective view of the gauge of FIG. 14, showing thepitch sensor supported above the propeller blade and ready to measurethe pitch of the blade relative to a “zero line” and also showing therake sensor rotated to the unused position away from the propellerblade;

[0026]FIG. 16 is a front elevation view of the gauge of FIG. 14, showingthe rake sensor being zeroed on the calibrating platen prior to loweringfor contact with the propeller blade;

[0027]FIG. 17 is a side elevation view of the gauge of FIG. 15, showingthe pitch sensor being zeroed on the calibrating platen prior tolowering for contact with the propeller blade;

[0028]FIG. 18 is a front elevation view of the gauge of FIG. 17, showingthe pitch sensor being zeroed on the calibrating platen;

[0029]FIG. 19 is a front view of the lower portion of the supportmember, showing the rake sensor in the lowered position and the pitchsensor in the uppermost unused position, both being rotatably coupled tothe optical encoder (shown in phantom) via a centralized axis;

[0030]FIG. 20 is a sectional view taken along the line 20-20 of FIG. 19,showing the rake sensor and pitch sensor to be rotatably coupled via anaxis to the optical encoder, the optical encoder being positioned on anopposite face of the support member as the pitch and rake sensors;

[0031]FIG. 21 is a side view of the rake sensor in contact with apropeller blade, the rake sensor pivoted at an angle relative to thezeroed position of FIG. 16;

[0032]FIG. 22 is a side view of the gauge showing the pitch sensorrotated into the lowered position and ready to measure the pitch of apropeller blade; and

[0033]FIG. 23 is a side view of the gauge of FIG. 22, showing the pitchsensor in contact with a propeller blade, the pitch sensor pivoted at anangle relative to the zeroed position shown in FIGS. 17 and 18.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] A gauge 10, as diagrammatically shown in FIGS. 1-11 and shown inan illustrative embodiment in FIGS. 14-18, is configured to support apitch sensor 16 and a rake sensor 18 above a propeller 8 fordetermination of the pitch and rake of a blade 26 of propeller 8. Pitchsensor 16 is diagrammatically shown in FIG. 2 positioned for measuringthe pitch of propeller blade 26. As pitch sensor 16 rotates to engagethe surface 28 of propeller blade 26, rotational sensor (illustrativelyan optical encoder) 22 senses the magnitude of rotation of pitch sensor16 from a zeroed position. Similarly, as shown in diagrammatic view inFIG. 3, rake sensor 18 is configured to be extended substantiallyradially across surface 28 of propeller blade 26 and any rotation fromzero of rake sensor 18 is measured with rotational sensor 22.

[0035] Gauge 10 illustratively includes a propeller mount comprising apost 12 and a base 14 for supporting the propeller 8 for pitch and rakemeasurement, as shown in FIG. 1. The post 12 serves as an axis-definingmember as will be described hereinafter. Propeller 8 is positioned onpost 12 with the cooperation of upper centering cone 30 and lowercentering cone 32, the propeller 8 being capable of rotational movementabout an axis that is coaxial with post 12. Gauge 10 further comprises aradial position arm 20 extending substantially perpendicularly from post12, the radial position arm 20 carrying rotational sensor 22, rakesensor 18, and pitch sensor 16. In one embodiment, rotational sensor 22is mounted to a support member 34, support member 34 being supported byradial position arm 20 for rotational movement as indicated by arrow 43relative to radial position arm 20 about an axis 42 passing throughradial position arm 20.

[0036] Rake sensor 18 and pitch sensor 16 combine to form a rotatingassembly, referred to as measurer 44 herein. Measurer 44 is positionedto be rotated about an axis 36 passing through rotational sensor 22, therotation being indicated by arrow 37 in FIGS. 1, 5-7, and 9-11. Whenmeasurer 44 is moved about axis 36, rotational sensor 22 senses therelative movement of measurer 44, and signals the relative movement tooutput device 38.

[0037] Operation of pitch sensor 16 can be seen in diagrammaticrepresentation in FIG. 2, wherein pitch sensor 16 rotates aboutrotational sensor 22 such that a surface 40 on pitch sensor 16 engagessurface 28 of propeller blade 26. The rotation of pitch sensor 16 aboutaxis 36 relative to a predetermined zero value is indicative of thepitch associated with a particular propeller 8. This relative rotationis then signaled to output device 38. As noted above, the pitch of apropeller is defined as the degree of slope of a surface 28 of propellerblade 26. Pitch is typically expressed as the theoretical distance apropeller would advance longitudinally in one revolution.

[0038] The similar operation of rake sensor 18 can be seen in FIG. 3,wherein a contact surface 46 of rake sensor 18 engages surface 28 ofpropeller blade 26, thereby measuring the rake of propeller blade 26along a radial line. Rotational sensor 22 senses the rotation of rakesensor 18 relative to a predetermined zero value, and signals therelative movement to output device 38. As noted above, the rake of apropeller is defined as the inclination of the propeller blade 26relative to a line extending radially and perpendicularly from the hub48.

[0039] One method of using the pitch sensor 16 is diagrammatically shownin FIGS. 4-7. After the propeller 8 is positioned on the propellermount, measurer 44 is shown in FIGS. 4 and 5 to be connected to thepropeller mount and positioned such that rake sensor 18 is above therotational sensor 22, and pitch sensor 16 is below the rotational sensor22. Gauge 10 is then assigned a neutral value, or “zeroed” prior totesting for the pitch of a propeller blade 26 by moving measurer 44 sothat pitch sensor 16 rests on calibrating platen 24, as shown from theside in FIG. 6. Once pitch sensor 16 has been positioned on calibratingplaten 24, output device 38 is “zeroed” such that the rotation of pitchsensor 16 relative to rotational sensor 22 is set to a value of zero.Thereafter, as shown in FIG. 7, calibrating platen 24 can be moved andpitch sensor 16 lowered such that surface 40 of pitch sensor 16 engagessurface 28 of propeller blade 26.

[0040] The engagement of pitch sensor 16 with propeller blade 26 causesmeasurer 44 to rotate about axis 36, thereby providing movement ofmeasurer 44 relative to rotational sensor 22. This relative movement issensed by rotational sensor 22, and in turn communicated via signals tooutput device 38. According to the disclosure, signals areillustratively electronic signals.

[0041] Gauge 10 is also configured to measure the rake of a propellerblade 26, as shown in FIGS. 8-11. As diagrammatically shown in FIGS. 8and 9, measurer 44 is arranged such that pitch sensor 16 is positionedabove rotational sensor 22 and rake sensor 18 is positioned belowrotational sensor 22 and ready for measurement of the rake of thepropeller blade 26. Furthermore, support member 34 is rotated about axis42 so that rake sensor 18 can measure the rake of propeller blade 26along a substantially radial line while rotating about axis 36.

[0042] Rake sensor 18 is prepared for use by lowering rake sensor 18 sothat it rests upon calibrating platen 24, as shown in FIG. 10. Once rakesensor 18 has been positioned on calibrating platen 24, output device 38is zeroed such that the position of rake sensor 18 relative torotational sensor 22 is set to a value of zero. Thereafter, as shown inFIG. 10, calibrating platen 24 can be moved and rake sensor 18 loweredsuch that surface 46 of rake sensor 18 engages surface 28 of propellerblade 26.

[0043] Similar to the operation of the pitch sensor above, theengagement of rake sensor 18 with propeller blade 26 causes measurer 44to rotate about axis 36, thereby providing movement of measurer 44relative to rotational sensor 22. This relative movement is sensed byrotational sensor 22, and in turn signaled to output device 38 forindication of the rake.

[0044] A typical propeller 8 is shown in FIGS. 12 and 13. Rake of thepropeller blade 26 is measured along a radial line, such as rakemeasurement line 50. The pitch of a propeller blade 26 can be measuredfrom any two points substantially equidistant from post 12, such as twopoints along pitch measurement line 52.

[0045] FIGS. 14-23 show an embodiment of gauge 110 wherein radialposition arm 120 is shown with detents 121, 123, 125, 127, 129, and 131for radially positioning arm 120 with the cooperation of lock 135 in anappropriate position for the measurement of either the pitch or the rakeof the propeller. A second lock 133 cooperates with detents (not shown)on the underside of detent block 137 to provide two locked positions forsupport member 134, support member 134 being configured for rotationabout axis 142. Gauge 110 includes a post 112, a base 114, and centeringcones 130, 132 for supporting a propeller 8 with blades 26. Lock 141fixes centering cones 130, 132 and propeller 8 in a vertically lockedposition.

[0046] As shown in FIGS. 14, 16 and 21, measurer 144 can be rotatedabout axis 136 to a rake-sensing mode where rake sensor 118 ispositioned for engagement of contact surface 146 with surface 28 ofpropeller blade 26. Axis 136 passes through optical encoder 122 formeasurement of the relative rotation of both rake sensor 118 and pitchsensor 116, similar to the function of rotational sensor 22, discussedabove. Illustratively, optical encoder 122 is a Model 1024 encoder ofthe S1 class, manufactured by US Digital Corp. While the illustratedembodiment uses a 1024 count encoder (i.e. 1024 pulses are signaled per90 degrees of rotation) for measuring, it should be understood thatencoders of various types are within the scope of the disclosure.

[0047] Calibrating platen 124 is provided for zeroing of both sensors118, 116. Rake sensor 118 includes a releasable lock 119 for selectivesliding movement of the rake sensor 118 relative to the measurer 144.

[0048] Additionally, as shown in FIGS. 15, 17, 18, 22, and 23, measurer144 can be further rotated about axis 136 to a pitch-measuring modewhere pitch sensor 116 is positioned to engage surface 28 of propellerblade 26. It will be appreciated that while pitch sensor 116 is shown tohave a first foot 160 and a second foot 162 for engagement with surface28 of propeller blade 26, other configurations permitting engagement ofpitch sensor 116 with surface 28 are within the scope of thisdisclosure. The feet 160, 162 or pointed engagers engage the curvedsurface 28 at two spaced apart points which establish an imaginary linetherebetween. The angle of this line, as reflected by the encoder 122,represents the pitch of the blade surface.

[0049] Display or output device 38 receives signals from optical encoder122 and is configured to calculate either the pitch or the rake of thepropeller blade surface 28 at a given moment. When it is determinedwhether pitch or rake will be measured, the corresponding pitch sensor116 or rake sensor 118 is first positioned on the calibrating platen 124and output device 38 is zeroed so that such a position is assigned azero value by the output device 38. The calibrating platen 124 is thenmoved out of the way and sensor 116 or 118 is rotated into position forcontact with the propeller blade 26. When sensor 116 or 118 is incontact with propeller blade 26, optical encoder 122 sends signalsrepresenting the rotated position of the sensor 116, 118 about axis 136of optical encoder 122 to the output device 38. Output device 38 isprompted by a user to report either the pitch or the rake.

[0050] Illustratively, output device 38 receives signals from opticalencoder 122 representing the relative rotation of sensors 116, 118 indegrees. If output device 38 is configured to produce a rakemeasurement, output device 38 simply displays the degree signal receivedfrom the optical encoder. If output device 38 is configured to provide apitch measurement, the following formula is used:

Pitch=Radius×2×pi×tan (degree input from optical encoder)

[0051] The output device receives input from a user as to the particularradius at which pitch measurement is taken. The various radius positionsare standardized and known in the art, and can be selected using detents121, 123, 125, 127, 129, and 131 of radial position arm 120 incooperation with lock 135.

[0052] While the disclosure is susceptible to various modifications andalternative forms, specific exemplary embodiments thereof have beenshown by way of example in the drawings and has herein be described indetail. It should be understood, however, that there is no intent tolimit the disclosure to the particular forms disclosed, but on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure asdefined by the appended claims.

[0053] There are a plurality of advantages of the present inventionarising from the various features of the pitch and rake gauge andassociated method described herein. It will be noted that alternativeembodiments of the gauge and associated method of the present inventionmay not include all of the features described yet still benefit from atleast some of the advantages of such features. Those of ordinary skillin the art may readily devise their own implementations of a pitch andrake gauge and associated method that incorporate one or more of thefeatures of the present invention and fall within the spirit and scopeof the present invention as defined by the appended claims.

What is claimed is:
 1. A gauge for measuring the pitch and the rake of ablade on a propeller, the gauge comprising a propeller mount configuredto engage a propeller, a measurer coupled to the propeller mount andadapted to engage the blade in a stationary position, a rotationalsensor adapted to gauge rotational movement of the measurer and providesignals representative of the gauged rotational movement, and a displayadapted to receive the signals and provide an output based on thesignals.
 2. The gauge of claim 1, wherein the rotational sensor iscoupled to the propeller mount and adapted to move between apitch-sensing mode and a rake-sensing mode.
 3. The gauge of claim 1,wherein the rotational sensor is an optical encoder.
 4. The gauge ofclaim 1, further comprising a calibrating platen adapted to provide areference from which to gauge rotational movement.
 5. An apparatus formeasuring the rake of a propeller blade, the apparatus comprising apropeller mount configured to engage the propeller, the propeller mounthaving an axis, an arm configured to couple to the propeller mount andextend radially therefrom, a support member attached to the arm, a rakesensor configured to engage the propeller blade, the rake sensor beingrotatably coupled to the support member, a rotational sensor coupled tothe rake sensor, the rotational sensor configured to determine therotation of the rake sensor relative to the support member and providesignals representative of the determined rotation, and a displayconfigured to receive the signals and provide an output based on thesignals.
 6. The apparatus of claim 5, wherein the rake sensor is astraight-edge configured to extend along a radial line relative to theblade of the propeller.
 7. The apparatus of claim 5, wherein therotational sensor is an optical encoder.
 8. The apparatus of claim 5,further comprising a pitch sensor coupled to the rake sensor.
 9. Theapparatus of claim 8, wherein the rotational sensor further determinesthe rotation of the pitch sensor relative to the support member andprovides signals representative thereof.
 10. The apparatus of claim 8,wherein the support member is configured to be moved between apitch-measuring mode and a rake-measuring mode.
 11. A method ofmeasuring a characteristic of a blade on a propeller, the propellerhaving an axis, the method comprising the steps of: positioning thepropeller on a propeller mount, connecting a measurer to the propellermount, assigning a neutral position for the measurer from whichrotational measurements will be based, moving the measurer into contactwith a selected position on the propeller blade and rotating themeasurer as necessary, determining the rotation of the measurer relativeto the neutral position, providing an electronic indication of therotation of the measurer relative to the neutral position.
 12. Themethod of claim 11, neutral-position-assigning step includes moving themeasurer into contact with a calibrating platen and zeroing the measurerwhile in that position.
 13. The method of claim 11, wherein the measurercomprises two feet in spaced apart relation, the two feet beingconfigured to contact the propeller blade at two points substantiallyequally distant from the axis of the propeller.
 14. The method of claim13, wherein the electronic indication provided is an indication of thepitch of the blade.
 15. The method of claim 11, wherein the measurercomprises a straight-edge configured to extend along a radial linerelative to the propeller blade.
 16. The method of claim 15, wherein theelectronic indication provided is an indication of the rake of theblade.
 17. An apparatus for measuring the pitch of a propeller blade,the apparatus comprising a propeller mount configured to support apropeller, the propeller mount having an axis, an arm configured tocouple to the propeller mount and extend radially therefrom, a supportmember attached to the arm, a pitch sensor configured to engage thepropeller blade, the pitch sensor being rotatably coupled to the supportmember, a rotational sensor coupled to the support member, therotational sensor configured to determine the rotation of the pitchsensor relative to the support member and provide signals representativeof the determined rotation, and a display configured to receive thesignals and provide an output based on the signals.
 18. The apparatus ofclaim 17, wherein the pitch sensor comprises two feet in spaced apartrelation, the two feet being configured to contact the propeller bladeat two points substantially equally distant from the axis of thepropeller mount.
 19. The apparatus of claim 17, wherein the rotationalsensor is an optical encoder.
 20. A gauge for measuring the pitch andthe rake of a blade on a propeller, the gauge comprising a propellermount configured to engage the propeller, the propeller mount having anaxis, an arm configured to couple to the propeller mount and extendradially therefrom, a support member rotatably attached to the arm forrotation about an axis between a pitch-sensing position and arake-sensing position, the support member extending from the arm suchthat its axis is substantially parallel to the propeller mount axis, thesupport member further having a first end coupled to the arm and asecond end opposite the first end, a pivot member rotatably coupled tothe second end of the support member, the pivot member having two endsand a pivot axis extending substantially perpendicularly through thesupport member, a pitch sensor coupled to one end of the pivot memberand configured to engage the propeller blade, a rake sensor coupled tothe other end of the pivot member and configured to engage the propellerblade, a rotational sensor coupled to the pivot member, the rotationalsensor configured to determine the rotation of the pivot member relativeto the support member and provide signals representative of thedetermined rotation, and a display configured to receive the signals andprovide an output based on the signals, wherein the pivot member can bepivoted about its axis between a position wherein the rake sensor ispresented to the propeller blade and a position wherein the pitch sensoris presented to the propeller blade.